The endogenous digitalis-like compounds (DLC)are steroid hormones synthesized and released from the adrenal gland.They are integrated in the feed-back system of the Hypothalami-Pituitary-Adrenal gland axis.One of their remarkable function is to induce apoptosis in malignant cells. Recently, accumulating data point to the possibility of using synthetic DLC as new anti-cancer drugs. Less is known about the endogenous metabolism of these compounds in cancer patients.